Adjustable sectional forming die



March 4, 1958 G. R. ALLEN I 2,825,335

ADJUSTABLE SECTIONAL FORMING DIE Filed Jan. 14, 1957 2 Sheets-Sheet 1 INVENTOR.

GE. ALLEN M r h 4, 195 G. a. ALLEN Y 2,825,385

ADJUSTABLE SECTIONAL FORMING DIE Filed Jan. 14, 1957 2 Sheetl-Sheet 2 INVENTOR.

s. 2. A L L 5 /v BY I ATTORNEY United States r 2,825,385 Patented Mar. 4, 1%53 ADJUSTABLE SECTIONAL FORMING DIE Gordon R. Allen, El Cajon, Califi, assignor to Rohr A ircraft Corporation, Chula Vista, Califi, a carperatlon of California Application January 14, 1957, Serial No. 633,985

8 Claims. (Cl. 153-32) This invention relates to the construction of a die against the curved face of which a metal strip is pulled to bend the strip to the shape of the die face. A machine of this type is shown in U. S. Patent to R. Seifried, 2,357,027 in which the shaping die is attached to a stationary table. It is customary to make such shaping dies of one piece of metal such as aluminum, and after the strip is bent and the tension thereon released, the end portions of the strip, due to the elasticity of the metal, spring out from the die. Due to this spring-back, the strip no longer has the desired shape to which the die face was made and it is usually necessary to cut away some metal from the end portions of the die to compensate for the spring-back. This is usually done by trial and error and after each cutting away of some metal, a metal strip is stretched against the die to determine whether the correct shape has been achieved. This is an expensive method for securing a die of the correct size and/or shape and a main object of my invention is to provide a die construction whereby this expense is greatly reduced.

17 whose inner end is attached to a pivot pin 18 journaled in a rearward extension 19 of main frame 15. A piston 20 is slidable within each cylinder 17 and is attached to the inner end of a piston rod 21 whose outer end carries a pivot pin 22 journaled in arm 13 or 14. Oil or other pressurized fluid is supplied to the inner end of cylinder 17 by a pipe 23 or supplied to the outer end of the cylinder by a pipe 24 from a source (not shown) of oil under pressure in a known manner. Each arm 13 and 14 has attached thereto a bracket 25 through which a pivot pin 26 passes which is attached to a long cylinder 27. Slidable within cylinder 27 is a piston 28 which is fastened to the outer end of a piston rod 29 whose inner end carries a chuck 30. Chucks 30 are adjustaole in a known manner to grip the opposite ends 31, 32 of metal strip 33 to be bent to the shape of die 16. Fluid under pressure is supplied to the inner end of cylinner 27 by a pipe 34 or to the outer end of the cylinder by a pipe 35 from a piping and valve system (not shown) or the type dlsclosed in the aforesaid patent which will malntaln a constant tension on strip 33 while it is bent against the face of die 10.

The die of Figs. 1 to 3 comprises four main parts, namely a generally semi-circular support plate 36 on the top or which 15 placed a fixed block 37 having a straight edge 38, an ad ustable block 39 having a straight edge 40 Furthermore, different metals spring back diflerent amounts after they are stretched around a die and released so that to make two parts composed of different metals to the same shape and size ordinarily requires two dies of slightly different shapes. For example, if an aluminum strip and a stainless steel strip are stretched against the same convex die face, due to stainless steel having approximately percent greater spring-back than aluminum, the ends of the formed stainless steel strip will be spaced apart by a distance substantially greater than the distance between the ends of the aluminum strip. In other words the two strips formed on the same die face are not the same size or shape. According to my invention the die is made adjustable so that the contour of the die face can be changed enough to vary the shape and size of strips which are stretched against it, thereby saving the cost of a second die.

Further objects of the invention will become apparent as the description thereof proceeds. For a better understanding of the invention, reference is made to the accompanying drawings, in which:

Fig. 1 is a top view of a die embodying the invention mounted in a stretch forming or bending machine parts of which are shown schematically;

Fig. 2 is an enlarged top view partly in section of the die shown in Fig. l

Fig. 3 is a sectional view of the die of Fig. 2 taken on line 3-3;

Fig. 4 is a top view, partly in section, showing a modified form of die and;

Fig. 5 is a sectional view of the die of Fig. 4 taken on line 5-5.

Referring toFig. 1 the die 10 is secured to the stationary table 1 1 of a stretch press 12 which has a pair of long arms 13, 14 pivoted to the main frame 15 of the 'press by pivot pins 16. Arms 13, 14 are oscillated simultaneously by hydraulic means comprising a cylinder disposed at an angle of approximately 10 degrees to edge 36 and a wedge 41. whose opposite faces contact edges 38 and 40. Along one side the top face of the wedge may be marked with llnear graduatlons 42 as for example, inches SllDdiVlCid into elghths, and block 39 has a cooperating index mark 43. The arcuate faces 44, 45 of blocks 3/, 39 meet at the point of tangency 46 to form a continuous die face which is covered by a band 47 of cold rolled steel about inch thick. A pair of countersunk screws 46 pass through band 47 and anchor its ends to blocks 37 and 39 so that band 47 acts as a spring to return block 39 to the position shown in Fig. 2 after it has been released from an adjusted position as later described. Plate 36 has an outer arcuate face 49 which extends out past band 47 and bent strip 33 to partly support the latter as it is being bent to shape.

Block 37 is attached to plate 36 by two bolts 50 and a pairof larger bolts 51 anchor the die to table 11 of the press. A spacer sleeve 52 surrounds each bolt 51 and keeps the die spaced at a level above table 11 (see Fig. 3). Die block 39 has two arcuate slots 53 extending therethrough and through which a pair of securing bolts 54 pass WfilCh are similar to bolts 50 and secure block 39 to support plate 36. One of the bolts 51 passes through an arcuate slot 55 which extends through plate 39, the slots 53 and 55 being concentric about the point'of tangency 46.

From the above it will be clear that by loosening bolts 54 and the bolt 51 which passes through slot 55, and moving wedge 41 toward the left in Fig. 2, die block 39 can be moved up about point 46 as a pivot point until its inclined edge 40 is again seated against wedge 41 when bolts 51 and 54 can again be tightened. This adjustment shortens the distance between the ends of band 47 and changes the shape of the peripheral face of the die by an amount depending on the distance wedge 41 was withdrawn. By setting wedge 41 at different positions as indicated by the graduations 42, it will be clear that the islhape or size of the die may be controlled within certain In using the die in stretch press 12, it is bolted to table 11 and fluid admitted to pipes 23 to move pistons 20 out in their cylinders until arms 13 and 14 are in alignment with each other. The chucks 35' are then moved toward each other until they grip the ends 31 of metal strip 33 by admitting pressurized fluid to pipes 2,8253% 7 r A c tially tangent to the center of metal band 47. Pres- 35; iStrip 33 at this 'time'is usually straight and substansurizedflui'cl is now admitted to pipes 34 to move pistons 28 in cylinders 27 by an amount sufficient to stretch strip connecting' its horizontal-flanges 58.: The'penipheral face ,ofthe ldiej notceir'cular but itscurvature changes along 7 "its lengthjjas shown. As inthe;previous'mo dification,t 92mm: an vq nth b t 1 l nd-54 ndx diu i j wedge tl to control the fshape gandfiofrflsize "of the bent or "strip, i Asi'the' bending of channel por'ting plates 3 6and 56 continnallyjbearagainst the proceeds, the supthe manner above described'to effect-the bending. While the use of the die for bending strips of rectangular'and channel cross sections has been illustrated, it 'is to be understood that strips of other sectional'shapes such as t i 33 somewhat beyond its elasticjlirnit. While iajconstant 5 2, T,' hat sections and others may be bent lby suitably tension is maintained on the' 'strip, pressurized fluid is shaping the die face which bears against th'e'strip V admitted to pipes 24 m movehpistonslt) and arms 13, While my improved'die hasbeen shown'mounted on 14 in until they reach the position shown in Fig.1. This a'stationary table, it may alsobe attached] to a rotary i movement has caused strip 33 to'be Qwrapped along the table suchtas the table 2 of. U. S;p'atentto"Ba th, 2,5141,- V peripheral face of band 47 and conformed substantially 830. In this case one endof'the strip to be bent W to its shape, Fluid is then admitted; to pipes 35 to move around the die isinserted ina clamp carried. by; the. pistons 28 in until strip 33' is no longer under tension 'table and its other" end is attachedtoia clanrpfconnected when its ends are released from chucks .30. iIf the strip 5 to the end of a piston rodfas shown in Figsw'l to 3743f 'is 'composed of mostfflexible metals such as stainless 5 said patent; Whensoused, adjustment of wedgei tl'eanj steel, aluminum or brasspdue to the elas'ticityof the matel5 compensates for different amounts of spring-back inthe rial, the portions of the strip in contact with ,the ends of same manner as "abovedescriljed; 1 a

band 4 7 :spring'out slightly and Jeavethe band after the This invention may be embodied in other iform's'or t tension .is released, this; phenomenon, being," known asv carried out in" other ways without .departingirom'the 1 spring-back; v This spring-back varies withe thecomposii spirit or; essential characteristicsfthereof.i jfhej present;

tion of the alloy beingbent and also with the heat treatembodiment of the invention is; therefore to beconsidered ment it has received. For example; hard stainless steel as in all respects illustrative and not restrictive, the scope 1 j has approximately 75 percent more spring-b'ack than the ot the invention being indicatd by the appended claims, 7 same material in the annealed condition; i I 'and all changes'which come within the meaning and range }If due to spring-back a formed part is too large that r of equivalency oi the claims are intended to'be' embraced is, the distance across its ends too great when it is taken therein. 7 t i v g i t 7 v off the, die, the operator loosens bolts 54- and 55 and o 7 Having thus described 'my invention, what'I clairnfas moves Wdge d l in E 1 by an amount which will j i new and useful and desire to secnre by LettersPatent is: 7 compensate for the oversize. A second; strip is then '2 1'. A shaping die having a curved peripheral face stretched in the manner described and when the tension 1 against which a strip of metal may: bestretched'tobend' onlhestrip has moved die block 39 in" against wedge the'strip to the shape of said face; said die comprising T 41} the m c i e -1 pp d Whil I p o 'h g fl a supporting plate; a first bloek attached'to'one'face of tightens bolts 54 and 55 to lock die block- 39 in place. said plate ina fixed position -thereon andhaving aplarn': The machine is again started and the forming completed. end face; a second block having aplane end face disposed iFrom'the above itwill beclear that by me'asuringsevat an aCute angl nto the end face of said 'firstfblock; l'al bent 33 1 formed W t different S g 70 W g means for detachably securingisaid second block tofsaid e 1, the QP Q Q a milk? UP 3 fi l l g 0 d -E 1 one face ofj said plate-"in adjusted position relative to a pi I i f Wedge 1 p 't z s i said first block; and :a' wedge havinga pairof conve rging of the bent strips produced. With 511C 3 i i fl P' surfaces incontact with the 'plane'end faces of said blocks; orator can'then set wedge 41 at the proper reading before f said blocks having curved peripheral surfaces which meet 7 Starting b P w th the assurance that h p g' 40 together totformth e curved peripheral facet ofthe die} 7 back of the material has'been cornpensated for and that 2 A shaping die a claimed in claim 1, in which said is the strip will be of the desired size and shape after forniwedge and n of aid blocks are provided: with scale 2 i i graduationsfand a cooperating index'marl; tojindicate In Certain casfiis r s band y be Omitted fl'flm the adjusted position'of said wedge: with reference to said the die v and the strip 33 stretched directly against the 49 one bl k; a i j 7 t t V i arcuate'fa'ces 44, of blocks 37 and 39. This may ;3,,A shaping die hi t ngi curved peripheral tace i cause a line or small projection to appear across the bent against hi h a tri pfngetal may be stretched to bend stripat the point of'tangency tfi foricertain positions of' thg strip t theha e of saidfiace; said jdie coniprisiug at i adjustment of Wedge 11 p f f n 47 P curved band of, flexible h ard materiahp pair of blocks 7 t t ventssuch surface defects and the band also acts as a Q h vi d Pg 'jphgjpgkfgggsifi ta t ith the i f f V spring to hold the blocks37, 39 in assembled relation f f id bandganda pairfof opposed end faces dis-i. while biasing block 39 away'fromblock 37 about tangent posed an t; angle to eachother; a commpnsupport' Point 45 85 V Pivotal fj l ksi'l l' forsaid blocks, one of said blocks being immovnbly-se: V of aluminum or an aluminum rich alloy, bending stainc d t id suppprt; a pluralityof screw threaded fast-t l Steel nip y against h 6 1 g 6 teners arrang id'toponnect' the [other' of' said blotzksfto V i the softer metal a tanid -we r iga y o h i face; said support in :anyfone of a plurality;offadjusted posi: Th presence of steel band 47 prevents this from help I flops; wedge having 'a ai -pf convergingfsurfiacesgiin w V 1 contact with said opposed end: faces; *and meansffor V Figs. 4 and 5' show a' di'e construction generally similarattaching saidband pea -erids-toi id1blocks j to that jabovej described except-as to the shape of, die 6 f 4, A shapingdie havingjai cnrvede peripheral face 7 blocks 37'," 39' and the presence of an additional supagainst'which-a-st n 'qtmeta mi v fl p ed ,andstretched porting plate '56 through which the several securing bolts to bend the stripi to lthe h e gf said f ace, saidfdie co n'f 50, 51 andj54 pass, In this case themetal strip :35" to ri i g a supporting plate firstblock having afplan'eend V be bentiis of channellfshapmand has a-vertical-weh 5? face; one onmore-thrzided' fasteners attaching-thejbon. 5

tom face of said block to thetop face' of said'gsup plate a ,ai ked aps ion' he ieon';iazssson wbl ta pla'ne 'e nd face disposed at'an acute anglettothe end ta o sa d-first .b' ss saa d i ot mt e inli-pnt cit' i thet'op face of said supporting plate; said'second block' ;ha ga p urality ot'slots'ie tending we n'itsiopga d bottom face s; threaded. fast'enet s' 'passing 'thi'oug hjsaid; T

V tsloj sa si s' idzsupnqt i sr atei e ureSa d supno Pl e ian zs 'c n b ock oeet erjwi h a flisecond bl ek, r -;in;a d si d a iu tedrposifien relative to, said fi sti lp k; Land a wedge'having-apa of converging surfacesin c'om flanges 58in theregions where the be'ndin'gf is taking place and prevent .undesirabieismali wrinkles l'froni form ingin the flanges; After theiends ot channel-strip 33" arefigrippedinthe'chuclcsiiti, the machine is operated in f aeaaseu tact with the plane end faces of said blocks, said blocks having curved peripheral surfaces which meet together to form the curved peripheral face of the die.

5. A shaping die as claimed in claim 4, in which a flexible metal band is attached to both of said blocks and substantially covers the entire curved peripheral surfaces thereof, the exposed face of said metal band constituting said curved peripheral face.

6. A metal-forming die comprising a pair of parallel spaced apart supporting plates; a first block disposed between and in contact with said plates and having a flat end face; means for securing said block to said plates in a fixed position; a second block disposed between and in contact with said supporting plates, said second block having a plane end face disposed at an acute angle to the end face of said first block; one or more threaded fasteners securing said second block to said supporting plates in adjusted position relative to said first block; and a wedge having a pair of converging surfaces in contact with the plane end faces of said blocks, said blocks having curved peripheral surfaces located between said supporting plates and which substantially meet together to provide a curved die face.

7. A die as claimed in claim 6, in which said second block is provided with one or more slots, said threaded fasteners passing through said slots and said supporting plates to secure said second block between said supporting plates in any one of a plurality of adjusted positions.

8. A die as claimed in claim 6, in which a band of hard flexible material is attached to both said blocks and substantially covers the curved peripheral surfaces thereof to provide a curved die face against which the metal to be formed is stretched.

References Cited in the file of this patent UNITED STATES PATENTS 677,121 Donovan June 25, 1901 1,189,823 Hulbert July 4, 1916 1,258,424 McLouth Mar. 5, 1918 1,406,384 Holmberg Feb. 14, 1922 2,292,731 Amiot Aug. 11, 1942 2,334,520 Walters Nov. 16, 1943 2,357,027 Seifried Aug. 29, 1944 2,514,830 Bath July 11, 1950 2,590,698 Hayden Mar. 25, 1952 2,729,264

Smith Jan. 3, 1956 

